My code is doing something weird

Hi everybody I'm still new to this whole building website stuff but any help will be much appreciated
and I'm still learning so bear with me if my code looks horrible.

Basically Previous and Next images are supposed to be on the same line closes to the left and one closes to the right,
I have a hover over previous and next to add some contrast when you go over it. When you go over the Next image it doesn't switch the image
nor can you click the link all the time but the previous does. My theory is that I'm not spacing them properly and it's creating an html/css mess.